Multi-axial connection system

ABSTRACT

A system and method for a multi-axial connection of an apparatus to bone. The system may include a fastener inserted into a body and a head of the fastener held within a chamber of the body through a combination of a retention ring, a pressure cap, a rod, and a compression element. The compression element applies force to the rod which, in turn, pushed on the pressure cap. The force on the pressure cap urges it against the head of the fastener and pushed it against the retention ring. The force on the retention ring causes it to expand to the walls of the chamber. Once the ring can no longer expand within the chamber, the head of the fastener is wedged between the retention ring and the pressure cap.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/105,021, filed Oct. 13, 2008, entitled “Multi-Axial ConnectionSystem,” and this application is a continuation-in-part of U.S.application Ser. No. 11/388,666, entitled “Multi-Axial ConnectionSystem,” filed Mar. 24, 2006 now U.S. Pat. No. 8,062,339, which is acontinuation-in-part of U.S. application Ser. No. 10/928,955, entitled“Multi-Axial Connection System,” filed Aug. 27, 2004 now abandoned. Theaforementioned applications are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The invention relates generally a multi-axial connection system forconnecting elements in varied moveable and/or fixed positions. Moreover,the invention generally relates to attaching a fastener assembly of themulti-axial connection system to a bone and further to a rod for thepurpose of bone fixation.

BACKGROUND OF THE INVENTION

Various systems for connecting fastener elements (e.g., pedicle screws)to elongated supports (e.g., rods) for the purposes of vertebralfixation have been proposed. Examples include the systems described inthe following U.S. Patents.

U.S. Pat. No. 5,466,237 relates to a variable locking stabilizer anchorseat and screw. More particularly, this patent relates to a boneinterface anchor provided for use with a stabilizer rod for the internalfixation of a spine. The anchor has a seat which accommodates thestabilizer rod and which receives a bone screw for the fixation of theseat to the bone. A compression member cooperates with the seat externalto the stabilizer rod and can be tightened to cause a compressive forceon the stabilizer rod. The stabilizer rod bears on a rounded surface ofthe bone screw so as to cause a mating interface between the seat andthe bone screw. Subsequently, the position of the seat relative to thebone screw can be locked.

U.S. Pat. No. 5,474,555 relates to a spinal implant system. Moreparticularly, this patent relates to an apparatus for the internalfixation of the spine. The apparatus comprises an assembly having atleast two anchors and an elongated stabilizer. The anchors each havemeans to hold the anchor to the bone, and include receiving means whichreceive the stabilizer as well as securing means which cooperate withthe receiving means by means of the interaction of mating threads tocause the application of compression on the stabilizer into thereceiving means.

U.S. Pat. No. 5,669,911 relates to a polyaxial pedicle screw. Moreparticularly, this patent relates to a polyaxial orthopedic device foruse with rod implant apparatus. The device includes a screw having acurvate head, a locking collar disposed therearound, and a receivingmember having a linearly tapered socket in which the screw and thecollar are nested. The locking collar is slotted and tapered, and has asemi-spherical interior volume into which the screw head is initiallypolyaxially held. The receiving member has a transverse channel formedin it for receiving a rod, and an axial bore having a linearly taperedchamber in the bottom portion thereof. The collar is inserted down thebore from the top to seat in the chamber, and the screw is subsequentlyinserted up through the bottom of the bore and into the collar. Thelinear taper of the chamber provides a radially inward force on thelocking collar when the collar is forced downward therein. This radiallyinward force causes the locking collar to crush lock against the head ofthe screw, therein locking the two at the given angulation. It is theplacement of the rod in the transverse channel, against the top of thecollar, and the subsequent locking down of the rod in the channel whichprovides the downward force against the locking collar, which in turnlocks the screw in its given angulation.

U.S. Pat. No. 5,879,350 relates to a multi-axial bone screw assembly.More particularly, this patent relates to a multi-axial bone screwassembly including a bone screw having a partially spherical head. Thebone screw head is truncated at an upper surface in which a toolreceiving recess is defined. The assembly includes a receiver memberincluding a central bore that defines a tapered recess to receive acontracting collet carrying the head of the bone screw. The bore of thereceiver member also defines a channel communicating with the recess andconfigured to receive a spinal rod therein. A portion of the channel isthreaded to receive a set screw above the rod. The assembly alsoincludes a contracting collet disposed between the rod and the head ofthe bone screw. The collet defines a partially spherical recess toreceive the head of the bone screw, and includes deflectable fingersthat substantially surround the screw head. As the set screw istightened into the receiver member, the set screw compresses the rodagainst the collet, which presses the collet into the tapered recess ofthe receiver member, thereby deflecting the fingers of the colletagainst the bone screw head.

U.S. Pat. No. 6,063,090 relates to a device for connecting alongitudinal support to a pedicle screw. More particularly, this patentrelates to a device used to connect a longitudinal support to a pediclescrew by an accommodating head having a channel to accommodate thelongitudinal support, wherein it is possible to freely choose from ormix laterally open, top open or closed accommodating heads. A top openaccommodating head facilitates, for example, insertion of thelongitudinal support, whereas a lateral opening enables lateralcorrections. The pedicle screw and the accommodating head are connectedvia a conical collet chuck in the accommodating head and by a sphericalhead on the pedicle screw.

U.S. Pat. No. 6,582,436 relates to a device for connecting alongitudinal support to a bone anchor. More particularly, this patentrelates to a device for connecting a longitudinal support to a boneanchor having a rounded head. The device includes a body defining achamber for receiving the rounded head of the bone anchor and a firstchannel for receiving the longitudinal support. Further, a first sleeveis slidable over the body for compressing the chamber, a second sleeveis slidable over the body for biasing the longitudinal support againstthe first sleeve, and a fastener is operatively associated with the bodyfor biasing the second sleeve toward the first sleeve. The forcesexerted on the second sleeve by the fastener are transferred to thefirst sleeve in a plane perpendicular to the central axis. Preferably,the longitudinal support contacts the first sleeve at first and secondcontact points or zones and one of the sleeves includes at least oneextended portion for contacting the other sleeve at least one additionalcontact point or zone.

U.S. Pat. No. 6,660,004 relates to a multi-axial bone screw assembly.More particularly, this patent relates to a bottom-loading multi-axialbone anchor apparatus. The apparatus includes a receiver member, a crownmember, a bone anchor and a retaining member. The receiver memberdefines an upper opening and a lower opening, which may form part of thesame opening, a channel, and a groove. The crown member and bone anchorare loaded into the lower opening of the receiver member, and theretaining member fits around the bone anchor and into the groove in thereceiver member. The bone anchor is capable of multi-axial positioningwith respect to the receiver member. An elongated member is placed inthe channel of the receiver member, contacting the crown member, and acompression member is applied via the upper opening. The compressionmember presses down on the elongated member, which presses down on thecrown member and locks the bone anchor between the crown member and theretaining member.

U.S. Pat. No. 6,740,086 relates to a screw and rod fixation assembly anddevice. More particularly, this patent relates to a screw and rodfixation assembly for fixing a screw and, optionally, a rod. The screwand rod fixation assembly includes a screw, fixing mechanism, asubstantially annular ring, rod seating mechanism, and lockingmechanism.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the presentinvention, wherein in one aspect a system and a method are provided thatin some embodiments includes a multi-axial connection system.

In accordance with one embodiment of the present invention, a fixationsystem is provided, which can comprise a body, wherein the body has afirst end and a second end, a body rod receiving channel disposedadjacent the first end of the body, a fastener head receiving chamberdisposed adjacent the second end of the body, wherein the fastener headreceiving chamber is tapered towards the second end of the body, andwherein the body rod receiving channel and the fastener head receivingchamber are operatively connected, a body engagement element fixablyattached to the body, a pressure cap slidably engaged with the bodyengagement element and disposed within the body, and a compressionelement configured to cooperate with the body to urge a rod, when therod is disposed within the body rod receiving channel, into contact withat least part of the pressure cap.

In accordance with another embodiment of the present invention, a methodof assembling a fixation system is provided and includes the steps ofconnecting a pressure cap to a body such that the pressure cap isslideably connected to the body, inserting a fastener having a fastenerhead into the body such that the head remains within a fastener headreceiving chamber of the body, and connecting a compression element tothe body.

In accordance with yet another embodiment of the present invention, afixation system is provided, which can comprise a body, having a firstend and a second end being offset from each other, an offset rodreceiving channel disposed adjacent the first end of the body, an offsetfastener head receiving chamber disposed adjacent the second end of thebody, wherein the offset fastener head receiving chamber is tapered, acompression element configured to cooperate with the body to urge thecompression element against a rod, when the rod is disposed within theoffset rod receiving channel, and an offset compression elementconfigured to cooperate with the body to urge the offset compressionelement against a head of a fastener, when the head of the fastener isdisposed within the offset fastener head receiving chamber.

In accordance with still another embodiment of the present invention, amethod of assembling a fixation system is provided and includes thesteps of inserting a fastener having a fastener head into an offset bodysuch that the head remains within an offset fastener head receivingchamber of the offset body, connecting a compression element to thebody, and connecting an offset compression element to the body.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded perspective view of a fastener assemblyaccording to an embodiment of the invention.

FIG. 2 shows a cross-sectional view of a partially assembled fastenerassembly according to the embodiment of FIG. 1 (for clarity, this FIG.does not include the rod or compression member of FIG. 1).

FIG. 3 shows an exploded perspective view of a fastener assemblyaccording to another embodiment of the invention.

FIG. 4 shows a cross-sectional view of a partially assembled fastenerassembly according to the embodiment of FIG. 3 (for clarity, this FIG.does not include the rod or compression member of FIG. 3).

FIG. 5 shows a side view of a fastener assembly according to anotherembodiment of the invention.

FIG. 6 shows a side view of a fastener assembly according to anotherembodiment of the invention.

FIG. 7 shows a side view of a fastener according to an embodiment of theinvention.

FIGS. 8A and 8B show, respectively, an elevational view and aperspective view of an offset design according to an embodiment of theinvention.

FIGS. 9A and 9B show, respectively, an elevational view and aperspective view of an offset design according to an embodiment of theinvention.

FIGS. 10A and 10B show, respectively, an elevational view and aperspective view of an offset design according to an embodiment of theinvention.

FIG. 11 shows a cross-sectional view of a fastener assembly according toan embodiment of the invention.

FIG. 12 shows a perspective, cross-sectional view of a fasteneraccording to an embodiment of the invention.

FIG. 13 shows a perspective view of a multi-axial body according to anembodiment of the invention.

FIG. 14 shows a cross-sectional view of a closed body according to anembodiment of the invention.

FIG. 15 shows a cross-sectional view of a reduction body according to anembodiment of the invention.

FIG. 16 shows a perspective view of a pressure cap according to anembodiment of the invention.

FIG. 17 shows a perspective view of a retention ring according to anembodiment of the invention.

FIG. 18 shows a perspective view of an offset set screw according to anembodiment of the invention.

FIG. 19 shows a side view of an alternative fastener according to anembodiment of the invention.

FIG. 20 shows a cross-sectional view of an offset fastener assemblyaccording to an embodiment of the invention.

FIG. 21 shows a cross-sectional, perspective view of a body according toan embodiment of the invention; and

FIG. 22 shows a perspective view of a pressure cap according to anembodiment of the invention.

FIG. 23 shows an elevation view of a flange according to an embodimentof the invention.

FIG. 24 shows a perspective view of an orientation plug according to anembodiment of the invention.

Among those benefits and improvements that have been disclosed, otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingfigures. The figures constitute a part of this specification and includeillustrative embodiments of the present invention and illustrate variousobjects and features thereof.

DETAILED DESCRIPTION

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely illustrative of the invention that may be embodied in variousforms. In addition, each of the examples given in connection with thevarious embodiments of the invention are intended to be illustrative,and not restrictive. Further, the figures are not necessarily to scale,some features may be exaggerated to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

For the purposes of describing and claiming the invention, the term“rod” is intended to refer to any elongated structure. Such an elongatedstructure may be solid or hollow and may have any desired cross-section(e.g., circular, oval, square, rectangular).

Further, for the purposes of describing and claiming the invention, theterm “interference fit” is intended to refer to physical contact betweentwo or more components.

The invention allows engagement of the pedicle screw in theaccommodating head after the pedicle screw has been inserted into bone.The invention also provides for a fixing mechanism for fixing a screw,wherein the fixing mechanism further includes an inner surface wallhaving a gripping portion and a non-gripping portion. Further, thepresent invention provides for a substantially annular ring for guidingand providing mechanical and frictional force to a screw head.Additionally, the present invention provides for a rod seating mechanismoperatively engaged to the screw head and including at least oneflexible portion capable of being compressed against a portion of a rodtherein. Finally, the present invention provides for a locking mechanismfor engaging the rod and the rod seating mechanism. The lockingmechanism includes a deflecting mechanism for deflecting the at leastone flexible portion of the rod seating mechanism against and around therod as the locking mechanism further engages the at least one flexibleportion of the rod seating mechanism.

Referring now to FIGS. 1 and 2, a first embodiment of the presentinvention is shown. As seen in these FIGS., Fastener Assembly 100 may beused in connection with mounting Rod 101 relative to a spine of apatient (of course, one or more such Fastener Assemblies may be usedwith one or more Rods). More particularly, Fastener Assembly 100 mayinclude Fastener 103 having Head 103A at a first end and Bone ConnectionElement 103B at a second end (Bone Connection Element 103B may beadapted for attachment on, in and/or to the spine). Further, Head 103Amay include at least one Deformation Element 103C thereon.

In one example (which example is intended to be illustrative and notrestrictive), at least a portion of Head 103A may be spherical. Inanother example (which example is intended to be illustrative and notrestrictive), Fastener 103 may be a bone screw and Bone ConnectionElement 103B may comprise threads. In another example (which example isintended to be illustrative and not restrictive), Fastener 103 may be acannulated bone screw (see Cannulation 103D of FIG. 2). In anotherexample (which example is intended to be illustrative and notrestrictive), Deformation Element 103C may substantially surroundCannulation 103D (e.g., where Cannulation 103D exits Head 103A). Inanother example (which example is intended to be illustrative and notrestrictive), Deformation Element 103C may be a substantially circularring protruding from Head 103A. In another example (which example isintended to be illustrative and not restrictive), Deformation Element103C (and/or any other portion of Fastener 103 (e.g., Head 103A or theentire Fastener 103)) may include a material which is: (a) softer than amaterial from which Rod 101 is formed; (b) harder than a material fromwhich Rod 101 is formed; or (c) of essentially the same hardness as amaterial from which Rod 101 is formed (e.g., the same material fromwhich Rod 101 is formed).

Still referring to FIGS. 1 and 2, it is seen that Fastener Assembly 100may include Body 105. Body 105 may have a first end and a second end,wherein Rod Receiving Channel 105A for receiving Rod 101 is disposedadjacent the first end of Body 105 and Fastener Head Receiving Chamber105B is disposed adjacent the second end of Body 105 (as seen in theseFIGS., Fastener Head Receiving Chamber 105B may be tapered towards thesecond end of Body 105 and Rod Receiving Channel 105A and Fastener HeadReceiving Chamber 105B may be operatively connected (e.g., a hole inBody 105 may connect Rod Receiving Channel 105A and Fastener HeadReceiving Chamber 105B)).

Further, Fastener Assembly 100 may include Retention Ring 107. ThisRetention Ring 107 may be sized to fit at least partially around Head103A when Head 103A is disposed within Fastener Head Receiving Chamber105B. In one example (which example is intended to be illustrative andnot restrictive), Retention Ring 107 may be, as shown in the FIGS., of a“split-ring” design.

Further still, Compression Element 109 may cooperate with Body 105 topush Rod 101, when Rod 101 is disposed within Rod Receiving Channel105A, into contact with at least part of Deformation Element 103C. Suchcontact between Rod 101 and Deformation Element 103C will deformDeformation Element 103C while pressing Head 103A towards the taperedend (i.e., narrower end) of Fastener Head Receiving Chamber 105B. Thisaction will serve to fix the angular relationship of Fastener 103relative to Rod 101.

More particularly, the angular relationship of Fastener 103 relative toRod 101 may be fixed at least in part due to: (a) an interference fit(caused by radial compression) between at least a portion of an outsidesurface of Head 103A and at least a portion of an inside surface ofRetention Ring 107; (b) an interference fit (caused by radialcompression) between at least a portion of an outside surface ofRetention Ring 107 and at least a portion of an inside surface ofFastener Head Receiving Chamber 105B; and/or (c) an interference fitbetween at least a portion of an outside surface of Rod 101 andDeformation Element 103C.

In one example (which example is intended to be illustrative and notrestrictive), Compression Element 109 may have threads which cooperatewith complementary threads of Body 105. In another example (whichexample is intended to be illustrative and not restrictive), CompressionElement 109 may have external threads which cooperate with complementaryinternal threads of Body 105 (e.g., Compression Element 109 may be a setscrew). In another example (which example is intended to be illustrativeand not restrictive), Compression Element 109 may have internal threadswhich cooperate with complementary external threads of Body 105 (e.g.,Compression Element 109 may be a nut). In another example (which exampleis intended to be illustrative and not restrictive), Compression Element109 may have one or more indentations, protrusions and/or drive facesfor receiving torque from a drive tool (e.g., the female hex).

Reference will now be made to the elements shown in FIGS. 1 and 2 inconnection with the description of an example installation procedure.Such an example installation procedure is applicable to this embodimentof the fastener assembly of the present invention and, of course, isintended to be illustrative and not restrictive.

More particularly, a guide wire may first be attached to a pedicle ofthe spine. The free end of the guide wire may then be passed throughFastener 103 (via Cannulation 103D). Fastener 103 (e.g., a pediclescrew) may then be inserted (e.g., screwed) into the pedicle of thespine. Of note, such a pedicle screw may be self-tapping into a holebored into the pedicle or the hole bored into the pedicle may bepre-tapped. Of further note, such a pedicle screw may be driven intobone with any desired tool (e.g., a hand or power driver applying torquethrough Rod Receiving Channel 105A and Fastener Head Receiving Chamber105B).

In one example (which example is intended to be illustrative and notrestrictive), such a pedicle screw may be driven into bone with a torqueapplying tool that engages one or more indentations, protrusions and/ordrive faces on Head 103A (e.g., the four scallops).

In one example (which example is intended to be illustrative and notrestrictive), Fastener 103 may be driven into bone by itself. Next, abody/retention ring assembly (e.g., including Body 105 having RetentionRing 107 already disposed within Fastener Head Receiving Chamber 105B)may be placed (or “snapped”) onto Fastener 103.

In this regard, as Body 105 is subsequently pushed onto Head 103A,Retention Ring 107 is pushed against the Back Wall 105C (FIG. 2) ofFastener Head Receiving Chamber 105B and Retention Ring 107 is free toexpand outward enabling Head 103A to pass through. Once Head 103A pushesthrough the bottom of Retention Ring 107, Head 103A remains captured(since Retention Ring 107 would have no room to expand as it was pulledforward by Head 103A towards the tapered (i.e., narrowed) end ofFastener Head Receiving Chamber 105B).

Next, Rod 101 may be placed in Rod Receiving Channel 105A (with Rod 101coming into contact with Deformation Element 103C).

Finally, as Compression Element 109 (e.g., a set screw) is threaded intoBody 105, Compression Element 109 clamps the components in a setposition (that is, Compression Element 109 pushes Rod 101 againstDeformation Element 103C (and, depending upon the size and shape of Rod101, Deformation Element 103C and Head 103A, against a portion of Head103A)). Of note, during this clamping process Deformation Element 103Cis deformed (e.g., to form a surface complementary to the portion of Rod101 causing the deformation) and the result is improved locking (e.g.,of the angular relationship between Rod 101 and Fastener 103). Offurther note, it is believed that Deformation Element 103C isparticularly useful in enabling secure locking of cannulated fasteners,such as cannulated pedicle screws (it is believed that a cannulation(without the use of a deformation element according to the presentinvention) may tend to compromise the ability to lock the multi-axialadjustability against the rod (e.g., due to a circular cross-section ofthe rod)).

In another example (which example is intended to be illustrative and notrestrictive), rather than driving Fastener 103 into bone by itself andthen placing a body/retention ring assembly thereon, Fastener 103 may becaptured within body/retention ring assembly as discussed above and thenthe entire body/retention ring/fastener assembly may be attached to thebone (e.g., by using a driving tool such as a hand or power driver todrive the pedicle screw through the hole provided in Body 105 betweenRod Receiving Channel 105A and Fastener Head Receiving Chamber 105B).

Referring now to FIGS. 3 and 4, another embodiment of the presentinvention is shown. This embodiment is similar to the embodiment shownin FIGS. 1 and 2 and, in this regard, the same elements will beidentified by the same reference numerals (such similar elements willnot be described again in detail). Of note, the main difference betweenthe embodiment of these FIGS. 3 and 4 and the embodiment of FIGS. 1 and2 is that in this embodiment Fastener Assembly 200 does not utilizeRetention Ring 107.

More particularly, Fastener Assembly 200 may again be used in connectionwith mounting Rod 101 relative to a spine of a patient (of course, oneor more such Fastener Assemblies may be used with one or more Rods).Further, Fastener Assembly 200 may include Fastener 103 (having Head103A, Bone Connection Element 103B and at least one Deformation Element103C).

Still referring to FIGS. 3 and 4, it is seen that Fastener Assembly 200may further include Body 105′ (Body 105′ may have a first end and asecond end, wherein Rod Receiving Channel 105A′ for receiving Rod 101 isdisposed adjacent the first end of Body 105′ and Fastener Head ReceivingChamber 105B′ is disposed adjacent the second end of Body 105′). As seenin these FIGS., Fastener Head Receiving Chamber 105B′ may be taperedtowards the second end of Body 105′ and a hole may be disposed throughBody 105′ to connect Rod Receiving Channel 105A′ and Fastener HeadReceiving Chamber 105B′.

Of note, the tapered (i.e., narrow) end of Fastener Head ReceivingChamber 105B′ may be made sufficiently small so as to prohibit Head 103Afrom passing therethrough (while Rod Receiving Channel 105A′ and thehole in Body 105′ connecting Rod Receiving Channel 105A′ to FastenerHead Receiving Chamber 105B′ may be made sufficiently large so as toallow Head 103A to pass therethrough).

In this regard, Fastener Assembly 200 may be installed by insertingFastener 103 through Body 105′ such that Head 103A comes to rest inFastener Head Receiving Chamber 105B′ (see FIG. 4). Fastener 103 maythen be inserted (e.g., into the pedicle of the spine) as discussedabove (e.g., a guide wire may be used to guide Fastener 103 and either aself-tapping bone screw may be driven into a hole in the bone or apre-tapped hole in the bone may be provided).

Finally, Compression Element 109 may cooperate with Body 105′ to pushRod 101, when Rod 101 is disposed within Rod Receiving Channel 105A′,into contact with at least part of Deformation Element 103C to deformDeformation Element 103C while pressing Head 103A towards the taperedend (i.e., narrower end) of Fastener Head Receiving Chamber 105B. Thisaction will fix the angular relationship of Fastener 103 relative to Rod101 (the angular relationship of Fastener 103 relative to Rod 101 may befixed at least in part due to: (a) an interference fit (caused by radialcompression) between at least a portion of an outside surface of Head103A and at least a portion of an inside surface of Fastener HeadReceiving Chamber 105B′; and/or (b) an interference fit between at leasta portion of an outside surface of Rod 101 and Deformation Element 103C.

Referring now to FIGS. 5 and 6, two other embodiments of a fastenerassembly body are shown. In this regard, it is noted that Body 105 ofFIGS. 1 and 2 has an upward facing Rod Receiving Channel 105A forreceiving Rod 101. Likewise, Body 105′ of FIGS. 3 and 4 has an upwardfacing Rod Receiving Channel 105A′ for receiving Rod 101. In contrast,it is seen in FIG. 5 that Body 500 includes a sideward facing RodReceiving Channel 501 for receiving Rod 101 (Fastener 103, CompressionElement 109 and Retention Ring 107 are shown in phantom and areessentially the same elements as described in detail above). Further, itis seen in FIG. 6 that Body 600 includes a “tunnel-type” Rod ReceivingChannel 601 for receiving Rod 101 (Fastener 103, Compression Element 109and Retention Ring 107 are shown in phantom and are essentially the sameelements as described in detail above). Of note, the embodiments ofthese FIGS. 5 and 6 may operate as discussed above (e.g., the body mayinclude a tapered chamber for facilitating an interference fit betweenthe components disposed therein).

Referring now to FIG. 7, another embodiment of a fastener for use withthe invention is shown. Of note, Fastener 700 is depicted here as a bonescrew, although other types of bone attaching mechanisms may, of course,be utilized (e.g., a shaft having a hook on the end). In any case, it isseen that in this embodiment Undercut 701 is provided (Undercut 701 maybe formed, for example, by a flattening of the Bottom of the Head 701Aof the bone screw and/or by a narrowing of a portion of the Shaft 701Bof the bone screw. By using such Undercut 701, Fastener 700 may provideincreased clearance in the area where Fastener 700 extends from the bodyof the fastener assembly (wherein such increased clearance may translateinto an increase in a maximum angle that Fastener 700 may obtain inrelation to the fastener body and/or the rod.

Referring now to FIGS. 8A and 8B, it is seen that these FIGS. show,respectively an elevational view and a perspective view of an offsetdesign according to an embodiment of the invention. In the example ofthese FIGS. 8A and 8B (which example is intended to be illustrative andnot restrictive), Body 805 includes a lateral offset (e.g., an 8 mmlateral offset) between Fastener Head Receiving Chamber 805B and RodReceiving Channel 805A. Further, Rod Receiving Channel 805A is angled(e.g., 50 degrees) from vertical (and from a vertical axis disposedthrough Fastener Head Receiving Chamber 805B). Of note, such offsetdesign may be used in a manner similar to that described with respect tothe non-offset designs (e.g., Body 105) disclosed herein (for example, afirst compression element, such as a set screw (not shown in these FIGS.8A and 8B), may be used to fix the rod (not shown in these FIGS. 8A and8B) relative to the body and a second compression element, such as a setscrew (not shown in these FIGS. 8A and 8B), may be used to fix the bonescrew (not shown in these FIGS. 8A and 8B) relative to the body).

Referring now to FIGS. 9A and 9B, it is seen that these FIGS. show,respectively an elevational view and a perspective view of an offsetdesign according to an embodiment of the invention. In the example ofthese FIGS. 9A and 9B (which example is intended to be illustrative andnot restrictive), Body 905 includes a lateral offset (e.g., an 11 mmlateral offset) between Fastener Head Receiving Chamber 905B and RodReceiving Channel 905A. Further, Rod Receiving Channel 905A is angled(e.g., 25 degrees) from vertical (and from a vertical axis disposedthrough Fastener Head Receiving Chamber 905B). Of note, such offsetdesign may be used in a manner similar to that described with respect tothe non-offset designs (e.g., Body 105) disclosed herein (for example, afirst compression element, such as a set screw (not shown in these FIGS.9A and 9B), may be used to fix the rod (not shown in these FIGS. 9A and9B) relative to the body and a second compression element, such as a setscrew (not shown in these FIGS. 9A and 9B), may be used to fix the bonescrew (not shown in these FIGS. 9A and 9B) relative to the body).

Referring now to FIGS. 10A and 10B, it is seen that these FIGS. show,respectively an elevational view and a perspective view of an offsetdesign according to an embodiment of the invention. In the example ofthese FIGS. 10A and 10B (which example is intended to be illustrativeand not restrictive), Body 1005 includes a lateral offset (e.g., a 14 mmlateral offset) between Fastener Head Receiving Chamber 1005B and RodReceiving Channel 1005A. Further, Rod Receiving Channel 1005A is angled(e.g., 15 degrees) from vertical (and from a vertical axis disposedthrough Fastener Head Receiving Chamber 1005B). Of note, such offsetdesign may be used in a manner similar to that described with respect tothe non-offset designs (e.g., Body 105) disclosed herein (for example, afirst compression element, such as a set screw (not shown in these FIGS.10A and 10B), may be used to fix the rod (not shown in these FIGS. 10Aand 10B) relative to the body and a second compression element, such asa set screw (not shown in these FIGS. 10A and 10B), may be used to fixthe bone screw (not shown in these FIGS. 10A and 10B) relative to thebody).

Of note, the offset designs may or may not utilize a screw with adeformation element. For example, a screw with a deformation element maybe utilized such that the compression element interfacing with the screwpresses down on and deforms the deformation element. In another example,a screw with a deformation element may be utilized such that thecompression element interfacing with the screw presses down on the screwhead itself but the compression element includes a cavity adjacent thescrew head and aligned with the deformation element such that thedeformation element does not deform. In another example, the screw headmay not have a deformation element at all.

Of further note, the offset designs may ease assembly of the fixationsystem (e.g., by providing a surgeon laterally offset/angled optionswhen connecting the spinal rod(s)).

In another embodiment (applicable to both the offset and non-offsetdesigns), the body may (before being fixed relative to the bone screw):(a) be circumferentially rotatable on the head of the bone screw aroundthe longitudinal axis of the bone screw; and/or (b) have a desireddegree of angular freedom (e.g., 26 degrees from the longitudinal axisof the bone screw (or 52 degrees from one side to the other).

FIG. 11 shows a cross-sectional view of a Fastener Assembly 1100according to another embodiment of the invention. The Fastener Assembly1100 may be used in connection with a mounting rod relative to a spineof a patient (of course, one or more such Fastener Assemblies 1100 maybe used with one or more rods). More particularly, the Fastener Assembly1100 may include a Fastener 1103 having a Head 1103A at a first end anda Bone Connection Element 1103B at a second end (FIG. 12). The Head1103A also includes a Drive Element 1106 (discussed below). The FastenerAssembly 1100 also includes a Body 1105, one or more Pins 1120, aPressure Cap 1140, a Retention Ring 1107, a Back Wall 1126 of theFastener Head Receiving Chamber 1105B, a Rod Receiving Channel 1105A, aLine 1148 (illustrates an example length of Pin Receiving Slots 1146(FIG. 16)) and a Compression Element 109 (not shown). The CompressionElement 109 engages the Body 1105, as previously described.

Referring now to FIG. 12, in one embodiment of the present invention,the Fastener 1103 comprises the Head 1103A at a first end and the BoneConnection Element 1103B at a second end (the Bone Connection Element1103B may be adapted for attachment on, in and/or to the spine). Atleast a portion of the Head 1103A may be spherical. In otherembodiments, the Head 1103A may include a flat surface on a top portion.The Head 1103A further comprises the Drive Element 1106 for engaging adrive tool to attach the Fastener 1103 to the spine. Such a DriveElement 1106 may be an indentation in the Head 1103A shaped to engage asquare drive tool, or alternatively any other drive tool having variousengaging shapes. The Fastener 1103 may be a bone screw and the BoneConnection Element 1103B may comprise Threads 1130 and a Cannulation1103D. The Threads 1130 may be of one or more lead designs. TheCannulation 1103D may be used as previously described herein. The tip ofthe Bone Connection Element 1103B may have Self-Tapping Flutes 1110 thatassist the Bone Connection Element to attach to the spine. In oneembodiment, there are three Self-Taping Flutes spaced about 120 degreesapart. In other embodiments, there may be two Self-Taping Flutes spacedabout 180 degrees apart. Other embodiments can include one or more thanthree Self-Taping Flutes spaced at appropriate angles.

In other embodiments, the Fastener 1103 may be a bone screw having astandard tip. The Fastener 1103 may further be a non-cannulated bonescrew with a tip having a self-tapping feature or a standard tip.

Referring now to FIG. 13, the Body 1105 may have a first end and asecond end, wherein the Rod Receiving Channel 1105A for receiving theRod is disposed adjacent the first end of the Body 1105 and the FastenerHead Receiving Chamber 1105B is disposed adjacent the second end of theBody 1105. The Rod Receiving Channel 1105A further includes Threads 1334for engaging with the Compression Element 109. Other embodiments mayforego the Threads 1334 in favor of other lockable means. In thisembodiment, the Rod can be inserted at the first end or simply throughthe Rod Receiving Channel 1105A.

As seen in FIGS. 11 and 13, the Fastener Head Receiving Chamber 1105Bmay be tapered towards the second end of the Body 1105, and the RodReceiving Channel 1105A and the Fastener Head Receiving Chamber 1105Bmay be operatively connected. In one embodiment, the operativeconnection may be a hole in the Body 1105 of sufficient diameter toallow passage of a drive tool through the hole as described in moredetail below. In another embodiment, the Body 1105 maybe a multi-axialbody as depicted in FIG. 13 comprising a u-shaped Rod Receiving Channel1105A. Alternatively, the Body 1105 may comprise other configurations,including but not limited to, a closed body having a Rib 1450 whichbridges the two sides of the Rod Receiving Channel 1105A at the firstend of the body (see FIG. 14), or a reduction body having RemovableExtensions 1560 connected at the first end the body (see FIG. 15).

As further shown in FIG. 13, the Body 1105 may further comprise one ormore Pin Mounting Cradles 1332. The Pin Mounting Cradles 1332 may bedisposed on either side of the Body 1105 in the walls of the RodReceiving Channel 1105A. In one embodiment, the Pin Mounting Cradles1332 are apertures that extend through the entire width of the walls ofthe Rod Receiving Channel 1105A. The Pin Mounting Cradles can have anouter diameter and an inner diameter, wherein the outer diameter islarger than the inner diameter (FIG. 11). The outer diameter allows theentire Pin 1120 to pass through while the inner diameter allows only aportion of the Pin 1120 to pass through, such as a shaft of the Pin1120, and not the Pin's head. Additionally, the outer diameter allowsthe Pins 1120 to be placed flushed against the Body 1105.

Within the Pin Mounting Cradles 1332, Pins 1120 are fixably mounted,such that the Pins 1120 protrude from the Pin Mounting Cradles 1332 intothe Rod Receiving Channel 1105A (see FIG. 11). One example method offixably mounting the Pins 1120 is by welding, however, other means offixably mounting the Pins 1332 can also be used.

It should be understood by one skilled in the art that the Pin MountingCradles 1332 could also be depressions in the inner portions of thewalls of the Rod Receiving Channel 1105A, or any other feature thatcould fixably retain the position of the Pins 1120. Alternatively, thePins 1120 may just be protrusions from the wall of the Rod ReceivingChannel 1105A which are part of the Body 1105 as constructed. The Body1105 can also include Cut Out 1370 and Holes 1375 located on varioussurfaces for mating with the Rod reduction and body insertioninstrumentation (not shown).

FIG. 14 shows a cross-section view of a Closed Body 1400 according to anembodiment of the present invention. The Closed Body 1400 can beessentially the same as the multi-axial body shown in FIG. 13, includingthe Threads 1334, the Cut Out 1370, Pins 1120, Pin Mounting Cradle 1332,Fastener Head Receiving Chamber 1405B, Pressure Cap 1140, and RetentionRing 1107, but includes Ribs 1450. The Ribs 1450 can be located in thefirst end of the Closed Body 1400. In this embodiment, the Rod can beinserted through the Rod Receiving Channel 1405A.

FIG. 15 shows a perspective view of a Reduction Body 1500 according toan embodiment of the present invention. The Reduction Body 1500, likethe multi-axial body, includes the Threads 1334, the Cut Out 1370, Pins1120, Pin Mounting Cradle 1332, Fastener Head Receiving Chamber 1505B,Pressure Cap 1140, and Retention Ring 1107, but further includes aRemovable Extensions 1560 and Break Regions 1570. The RemovableExtensions 1560 are configured to break off at the Break Regions 1570after a set screw reduces the Rod into the Body below the Break Region1570. The Rod Receiving Channel 1505A is elongated so that a set screwengages the Threads 1334 and is threaded down the Removable Extensions1560 and into the Body 1500 to reduce the Rod for the purposes of aidingdeformity correction. Once the Removable Extensions 1560 are broken offthen the Reduction Body resembles the multi-axial body 1105.

Now referring to FIG. 16, the Pressure Cap 1140 may have a first end anda second end, wherein a Pressure Cap Rod Receiving Channel 1142 forreceiving the Rod is disposed adjacent the first end of the Pressure Cap1140 and a Head Receiving Face 1144 is disposed adjacent the second endof the Pressure Cap 1140. The Pressure Cap Rod Receiving Channel 1142may have a “V” shape so as to increase the Rod contact area. As seen inFIG. 16, the Head Receiving Face 1144 may be tapered towards the firstend of the Pressure Cap 1140 and form a conical shape. The top end ofthe conical shape (near the first end of the Pressure Cap) has a smallerdiameter than the bottom end (near the second end of the Pressure Cap).Alternatively, the Head Receiving Face 1144 may consist of a partiallyspherical diameter whose diameter is smaller than that of the Head 1103Aof the Fastener 1103. The Pressure Cap Rod Receiving Channel 1142 andthe Head Receiving Face 1144 may be operatively connected. In oneembodiment, the operative connection may be a hole in the Pressure Cap1140 of sufficient diameter to allow passage of a drive tool through thehole as described in more detail below.

The Pressure Cap 1140 may comprise one or more Pin Receiving Slots 1146.The Pin Receiving Slots 1146 are disposed on either side of the PressureCap 1140 in the walls of the Pressure Cap Rod Receiving Channel 1142. Inone embodiment, the Pin Receiving Slots 1146 are apertures that canextend through the entire width of the walls of the Rod ReceivingChannel 1142. The Pin Receiving Slots 1146 can run the length of Line1148 (shown in FIG. 11) of an axis of the Pressure Cap 1140.

As seen in FIG. 11, the Pressure Cap 1140 can be inserted into the Body1105 such that the first end and the second end of the Body 1105 areadjacent to the first end and second end of the Pressure Cap 1140,respectively. When the Pressure Cap 1140 is inserted into the Body 1105,the Pin Receiving Slots 1146 engage the Pins 1120. The Pin ReceivingSlots 1146 are elongated so as to allow the Pressure Cap to slideablymove within the Body 1105 between the first end and second end of theBody 1105. Such movement is restricted by contact between the walls ofthe Pin Receiving Slot 1146 and the Pins 1120. The length of Line 1148of the Pin Receiving Slots 1146 is such that when the Head 1103A isdisposed within the Fastener Head Receiving Chamber 1105B and theCompression Element 109 is tightened, there is clearance between thePins 1120 and the ends of the Pin Receiving Slots 1146 adjacent to thefirst end of the Pressure Cap 1140.

It should be understood by one skilled in the art that the Pin ReceivingSlot 1146 could also be depressions in the outer portions of the wallsof the Pressure Cap Rod Receiving Channel 1142, or any other featurethat could slideably engage the Pins 1120.

It should be further noted that is possible for the Pin Mounting Cradles1332 and the Pins 1120 to reside on the Pressure Cap 1140, with the Pins1120 protruding from the exterior of the Pressure Cap 1140, and the PinReceiving Slots 1146 residing on the Body 1105.

Also, other embodiments of each of the Bodies 1105, 1400, 1500 may besized differently, such that the distance between the Rod ReceivingChannel 1105A, 1405A, 1505A, respectively, and the Fastener HeadReceiving Chamber 1105B, 1405B, 1505B, respectively, varies between theembodiments. In such embodiments, the Pressure Cap 1140 may beappropriately size by varying the distance between the Pressure Cap RodReceiving Channel 1142 and the Head Receiving Face 1144 so that thePressure Cap 1140 may function as described in connection with previousembodiments.

Further, Fastener Assembly 1100 of FIG. 11 may include the RetentionRing 1107. This Retention Ring 1107 may be constructed to fit at leastpartially around the Head 1103A when the Head 1103A is disposed withinthe Fastener Head Receiving Chamber 1105B. When the Retention Ring 1107is fitted around the Head 1103A, the Retention Ring 1107 expands andcontracts such that the Head 1103A cannot be extracted from the FastenerHead Receiving Chamber 1105B through the second end of the Body 1105. Inone embodiment, the Retention Ring 1107 may be, as shown in the FIG. 17,of a “split-ring” design. The Retention Ring 1107 may comprise a firstend and a second end where a Slit 1762 extends fully between both ends.Further the Exterior Wall 1764 of the Retention Ring 1107 may taper fromthe first end to the second end having a substantially similar taper tothat of the Fastener Head Receiving Chamber 1105B. The Retention Ring1107 may further comprise an Upper Inner Taper 1766 adjacent to thefirst end, which has a taper substantially similar to the taper of theExterior Wall 1764, a Cylinder 1768 adjacent to the second end, and aLower Inner Taper 1770 disposed between the Upper Inner Taper 1766 andthe Cylinder 1768, having a taper greater than that of the Upper InnerTaper 1766.

In operation, the Compression Element 109 may cooperate with the Body1105 to push a Rod, when the Rod is disposed within the Rod ReceivingChannel 1105A, into contact with at least part of the Pressure Cap RodReceiving Channel 1142. Such contact between the rod and the PressureCap Rod Receiving Channel 1142 will slideably move the Pressure Cap 1140causing the Head Receiving Face 1144 to press the Head 1103A towards thetapered end (i.e., narrower end) of the Fastener Head Receiving Chamber1105B. This action will serve to fix the angular relationship ofFastener 1103 relative to the rod.

More particularly, the angular relationship of Fastener 1103 relative tothe Rod may be fixed at least in part due to: (a) an interference fit(caused by radial compression) between at least a portion of an outsidesurface of Head 1103A and at least a portion of an inside surface ofRetention Ring 1107; (b) an interference fit (caused by radialcompression) between at least a portion of an outside surface ofRetention Ring 1107 and at least a portion of an inside surface ofFastener Head Receiving Chamber 1105B; and/or (c) an interference fitbetween at least a portion of the Head Receiving Face 1144 and anoutside surface of Head 1103A.

Another embodiment of the Fastener Assembly 1100, as seen in FIG. 23,may include the attachment of a Flange 1150 at the opening of theFastener Head Receiving Chamber 1105B. The Flange 1150 may be a singlepiece including a Flange Slot 1152. The single piece may be of anyshape, for example, circular or U-shaped, or it may comprise multiplepieces, any of which, when attached to the Fastener Assembly 1100 createa Flange Slot 1152. The Flange Slot 1152, may be a hole in the Flange1150 or a space between pieces of the Flange 1150. The Bone ConnectionElement 103B of the Fastener 1103 may extend through the Flange Slot1152. The Flange 1150 may be attached in a variety of ways, including,for example, welding, gluing, or attaching via a connection element,before or after inserting the Fastener 1103 into the Fastener HeadReceiving Chamber 1105B. The Flange 1150 may restrict the angularrelationship of Fastener 1103 relative to the Rod by limiting themovement of the Fastener 1103 to one plane coinciding with the FlangeSlot 1152.

Still another embodiment, as seen in FIG. 24, may include an OrientationPlug 1160 to restrict the angular relationship of Fastener 1103 relativeto the Rod. The Orientation Plug 1160 may have an Engagement Feature1162, a Rod Receiving Face 1164, and a Projection 1166. The EngagementFeature 1162 may be shaped to engage with the Pin Receiving Slots 1146(shown in FIG. 16) of the Pressure Cap 1140. The Rod Receiving Face 1164may be shaped similarly to the Pressure Cap Rod Receiving Channel 1142(shown in FIG. 16) so that it may contact the Rod but not interfere withthe contact between the Rod and the Pressure Cap Rod Receiving Channel1142. The Projection 1166 may be shaped such that it contacts the DriveElement 1106 (shown in FIG. 12) of the Fastener 1103, limiting themovement of the Fastener in at least one direction.

Reference will now be made to the elements shown in FIG. 11 inconnection with the description of an example installation procedure.Such an example installation procedure is applicable to this embodimentof the fastener assembly of the present invention and, of course, isintended to be illustrative and not restrictive.

More particularly, a guide wire may first be attached to a pedicle ofthe spine. The free end of the guide wire may then be passed through theFastener 1103 (via the Cannulation 1103D (FIG. 12)). The Fastener 1103(e.g., a pedicle screw) may then be inserted (e.g., screwed into) intothe pedicle of the spine. Of note, such a pedicle screw may beself-tapping into a hole bored into the pedicle or the hole bored intothe pedicle may be pre-tapped. Of further note, such a pedicle screw maybe driven into bone with any desired tool (e.g., a hand or power driverapplying torque through the hole provided in the Body 1105 between theRod Receiving Channel 1105A and the Fastener Head Receiving Chamber1105B, and the hole provided in the Pressure Cap 1140 between thePressure Cap Rod Receiving Channel 1142 and the Head Receiving Face1144).

In one embodiment, such a pedicle screw may be driven into bone with atorque applying drive tool that engages one or more indentations,protrusions and/or drive faces on the Head 1103A (see, e.g., DriveElement 1106 of Head 1103A in FIG. 12).

In one embodiment, the Fastener 1103 may be driven into bone by itself.Next, a body/retention device/pressure cap assembly (e.g., including theBody 1105 having the Retention Ring 1107 already disposed within theFastener Head Receiving Chamber 1105B, the Pins 1120 already fixablydisposed within the Pin Mounting Cradles 1332, and the Pressure Cap 1140already slideably engaged on the Pins 1332) may be placed (or “snapped”)onto Fastener 1103.

In this regard, as the Body 1105 is subsequently pushed onto the Head1103A (or vice-versa), the Retention Ring 1107 is pushed against theBack Wall 1126 (see FIG. 11) of the Fastener Head Receiving Chamber1105B and the Retention Ring 1107 is free to expand outward enabling theHead 1103A to pass through. Once the Head 1103A pushes through thebottom of the Retention Ring 1107, the Head 1103A remains captured(since the Retention Ring 1107 would have no room to expand as it waspulled forward by the Head 1103A towards the tapered (i.e., narrowed)end of the Fastener Head Receiving Chamber 1105B.

Simultaneously, as the Head 1103A passes through the Retention Ring1107, the Head 1103A contacts the Head Receiving Face 1144 (shown inFIG. 16) and slideably pushes the Pressure Cap 1140 toward the first endof the Body 1105. The length of the Pin Receiving Slots 1146 (shown inFIG. 16) is such that when the Head 1103A is inserted into the FastenerReceiving Chamber 1105B, there is enough clearance between the ends ofthe Pin Receiving Slots 1146 and Pins 1120 to allow for assembly.

Next, the rod may be placed in the Rod Receiving Channel 1105A and thePressure Cap Rod Receiving Channel 1142 (shown in FIG. 16).

Finally, as the Compression Element 109 (e.g., a set screw) is threadedinto the Body 1105, the Compression Element 109 clamps the components ina set position. That is, the Compression Element 109 pushes the rodagainst the Pressure Cap Rod Receiving Channel 1142 (shown in FIG. 16),which pressure slideably pushes the Pressure Cap 1140 toward the secondend of the Body 1105. Then the Head Receiving Face 1144 pushes the Head1103A against the Retention Ring 1107, which in turn pushes against thetapered inner walls of the body. Of note, during this clamping processthe movable nature of the Pressure Cap 1140 allows for some clearancebetween the Pins 1120 and Pin Receiving Slots 1146 (shown in FIG. 16)enabling clamping of the Head 1103A to take place.

If using the Flange 1150, it may be attached to the Fastener Assembly1100 at any point after the Body 1105 is pushed onto the Head 102 (orvice-versa). Further, if using the Orientation Plug 1160, it may beinserted into the Fastener Assembly 1100 at any point before insertingthe Rod.

In another embodiment, it is possible, rather than driving Fastener 1103into bone by itself and then placing a body/retention ring/pressure capassembly thereon, the Fastener 1103 may be captured withinbody/retention ring/pressure cap assembly as discussed above and thenthe entire body/retention ring/pressure cap/fastener assembly may beattached to the bone (e.g., by using a driving tool such as a hand orpower driver to drive the pedicle screw through the hole provided in theBody 1105 between the Rod Receiving Channel 1105A and the Fastener HeadReceiving Chamber 1105B, and the hole provided in the Pressure Cap 1140between the Pressure Cap Rod Receiving Channel 1142 and the HeadReceiving Face 1144).

In this embodiment, if using the Flange 1150, it may be attached to theFastener Assembly 1100 at any point, for example, the manufacturer mayconnect the Flange 1150 to the Fastener Assembly 1100. If theOrientation Plug 1160 is used, then its insertion into the FastenerAssembly 1100 must wait until after the Fastener is driven into thebone.

Another embodiment (not shown) of the present invention is similar tothe embodiment shown in FIG. 11 and, in this regard, the same elementswill be identified by the same reference numerals (such similar elementswill not be described again in detail). The difference between theembodiments is that in this embodiment the Fastener Assembly 1100 doesnot utilize Retention Ring 1107, and that the tapered (i.e., narrow) endof the Fastener Head Receiving Chamber 1105B may be made sufficientlysmall so as to prohibit the Head 1103A from passing therethrough (whilethe Rod Receiving Channel 1105A, the hole in the Body 1105 connectingthe Rod Receiving Channel 1105A to the Fastener Head Receiving Chamber1105B, may be made sufficiently large so as to allow Head 1103A to passtherethrough).

It is further envisioned that the angular relationship of Fastener 1103relative to the Rod may be restricted by the shape of the opening of thetapered end of the Fastener Head Receiving Chamber 1105B through whichextends the Fastener 1103. An example (not shown) of such an opening maybe shaped like a slot, and the movement of the Fastener 1103 may berestricted to a single plane coinciding with the slot. The Fastener HeadReceiving Chamber 1105B may also be extend to encompass more of the BoneConnection Element 103B to greater restrict the movement of the Fastener1103.

In this regard, the Fastener Assembly 1100 may be installed by insertingthe Fastener 1103 through the Body 1105, such that the Head 1103A comesto rest in the Fastener Head Receiving Chamber 1105B. The Pressure Cap1140 is the inserted into the Body 1105, and the Fastener 1103 may thenbe inserted (e.g., into the pedicle of the spine) as discussed above(e.g., a guide wire may be used to guide the Fastener 1103 and either aself-tapping bone screw may be driven into a hole in the bone or apre-tapped hole in the bone may be provided).

Finally, the Compression Element 109 may cooperate with the Body 1105 topush the rod, when the rod is disposed within the Rod Receiving Channel1105A, into contact with at least part of the Pressure Cap Rod ReceivingChannel 1142 to slideably move the Pressure Cap 1140 while pressing theHead 1103A towards the tapered end (i.e., narrower end) of the FastenerHead Receiving Chamber 1105B. This action will fix the angularrelationship of Fastener 1103 relative to the rod (the angularrelationship of the Fastener 1100 relative to the rod may be fixed atleast in part due to: (a) an interference fit (caused by radialcompression) between at least a portion of an outside surface of theHead 1103A and at least a portion of an inside surface of the FastenerHead Receiving Chamber 1105B; and/or (b) an interference fit between atleast a portion of an outside surface of at least a portion of anoutside surface of the Head 1103A and the Head Receiving Face 1144).

Referring now to FIG. 18, an Offset Set Screw 1800 has a first end and asecond end, wherein an Offset Drive Feature 1850 is disposed adjacent tothe first end of the Offset Set Screw 1800 and an Offset Head ReceivingFace 1852 is disposed adjacent to the second end of the Offset Set Screw1800. The Offset Head Receiving Face 1852 may be tapered toward thefirst end of the Offset Head Receiving Face 1852 along an inner surfaceand forms a conical shape inner surface. The conical shape inner surfaceis constructed and designed to receive the Head 1103A of Fastener 1103.Alternatively, the Offset Head Receiving Face 1852 may consist of apartially spherical diameter whose diameter is smaller than that of theHead 1103A of the Fastener 1103.

In one embodiment, the diameter of the Offset Head Receiving Face 1852at the first end is larger than the diameter at the second end and inanother embodiment, the diameter of the Offset Head Receiving Face 1852at the first end is less than the diameter at the second end. The OffsetDrive Feature 1850 and the Offset Head Receiving Face 1852 may beoperatively connected through a hole in the Offset Set Screw 1800.Threads 1854 are configured to engage the threads of Offset FastenerAssembly 2000, described below.

In an alternative embodiment, the Offset Set Screw 1800 may be comprisedof multiple pieces. One such embodiment may include a first piece, whichmay embody the Offset Head Receiving Face 1852, to contact the Head1103A of Fastener 1103, and a second piece, such as the CompressionElement 109 (which may embody a set screw), to lockably retain the firstpiece. The first piece may be placed in or threaded into the OffsetFastener Head Receiving Chamber 2022 of the Offset Fastener Assembly2000, described below, and the second piece may be fastened into theOffset Fastener Head Receiving Chamber 2022 retaining the first piece inplace.

Referring now to FIG. 19, wherein another embodiment of a Fastener 1900for use with the invention is shown. The Fastener 1900 is depicted hereas a bone screw, although other types of bone attaching mechanisms may,of course, be utilized (e.g., a shaft having a hook on the end). In anycase, it is seen that in this embodiment an Undercut 1901 is providedand may be formed, for example, by providing a Bottom of the Head 1901Aof the head of the bone screw and/or by providing a Shaft 1901B of thebone screw. By using such an Undercut 1901, the Fastener 1900 mayprovide increased clearance in the area where the Fastener 1900 extendsfrom the body of the Fastener Assembly 1100, wherein such increasedclearance may translate into an increase in a maximum angle that theFastener 1900 may obtain in relation to the fastener body and/or therod. Cannulation 1902 is also shown in FIG. 19 for the purposespreviously described.

Referring now to FIG. 20, an alternative embodiment of the invention isshown. The Offset Fastener Assembly 2000 may be used in connection witha Rod 101 relative to a spine of a patient (of course, one or more suchFastener Assemblies may be used with one or more rods). Moreparticularly, the Offset Fastener Assembly 2000 may include the Fastener1103, an Offset Body 2020, Offset Set Screw 1800, Retention Ring 1107,and the Compression Element 109.

The Offset Body 2020 includes a lateral offset (e.g., an 8 mm, 11 mm, or14 mm lateral offset) between the Offset Fastener Head Receiving Chamber2022 and the Offset Rod Receiving Channel 2024. Further, the Offset RodReceiving Channel 2024 is angled (e.g., 15 degrees, 25 degrees, or 50degrees) from vertical (and from a vertical axis disposed through theOffset Fastener Head Receiving Chamber 2022). It is envisioned that thelateral offset between the Offset Fastener Head Receiving Chamber 2022and the Offset Rod Receiving Channel 2024 is not limited to the exampledistances above, and that the distance of the offset may be of anylength. It is further envisioned that the angle of the Offset RodReceiving Channel 2024 is not limited to the example angles above, andthat the angle may be of any degree and in any direction.

Another embodiment (not shown) of the Offset Fastener Assembly 2000 mayinclude the attachment of a Flange at the opening of the Offset FastenerHead Receiving Chamber 2022. The Flange may be a single piece includinga Flange Slot. The single piece may be of any shape, for example,circular or U-shaped, or it may comprise multiple pieces that whenattached to the Offset Fastener Assembly 2000 to create the Flange Slot.The Bone Connection Element 103B of the Fastener 1103 may extend throughthe Flange Slot. The Flange may be attached in a variety of ways,including, for example, welding, gluing, or attaching via a connectionelement, before or after inserting the Fastener 1103 into the OffsetFastener Head Receiving Chamber 2022. The Flange may restrict theangular relationship of Fastener 1103 relative to the Rod by limitingthe movement of the Fastener 1103 to one plane coinciding with theFlange Slot.

Such offset design may be used in a manner similar to that describedwith respect to the non-offset designs (e.g., the Body 1105) disclosedherein. FIG. 20 depicts one such embodiment where the CompressionElement 109, such as a set screw, may be used to fix the Rod 101relative to the Offset Body 2020 and the Offset Set Screw 1800 may beused to fix the Fastener 1103 relative to the Body.

Of further note, the offset designs may ease assembly of the fixationsystem (e.g., by providing a surgeon laterally offset/angled optionswhen connecting the spinal rod(s)).

Referring now to FIG. 21, another embodiment of the Fastener Assembly1100 may comprise a Body 2100. The Body 2100 may have a first end and asecond end, wherein a Compression Element Receiving Chamber 2122 isdisposed adjacent the first end of the Body 2100 and a Fastener HeadReceiving Chamber 2105B is disposed adjacent the second end of the Body2100. A Rod Receiving Channel 2105A for receiving the Rod is disposedbetween the Compression Element Receiving Chamber 2122 and Fastener HeadReceiving Camber 2105B. The Compression Element Receiving Chamber 2122further includes Threads 2334 for engaging with the Compression Element109. The Threads 2334 incorporate a Tab Channel 2336 to allow a PressureCap 2140 to slideably move within Body 2100. In this embodiment, the Rodcan be inserted through an Opening 2128 in a wall of the Body 2100 orsimply through the Rod Receiving Channel 2105A.

As seen in FIG. 21, the Fastener Head Receiving Chamber 2105B may betapered towards the second end of the Body 2100, and the CompressionElement Receiving Chamber 2122, the Rod Receiving Channel 2105A, and theFastener Head Receiving Chamber 2105B may be operatively connected. Inone embodiment, the operative connection may be a hole in the Body 2100of sufficient diameter to allow passage of a drive tool through the holeas described herein. Further a Retention Ring 1107 may be disposedwithin the Fastener Head Receiving Chamber 2105B.

The Body 2100 may further comprise at least one Pin Mounting Cradle 1332to fixably retain a Pin 2120. The Pin Mounting Cradle 1332 is disposedon a side of the Body 2100 in a wall of the Rod Receiving Channel 2105Aor a wall of the Compression Element Receiving Chamber 2122. In oneembodiment, the Pin Mounting Cradle 1332 is an aperture that extendsthrough the entire width of the wall of a Tab Channel 2336. The PinMounting Cradle 1332 and the Pin 2120 are otherwise substantiallysimilar to the Pin Mounting Cradle 1332 and the Pin 1120 (shown in FIG.11) as described above, except that Pin 2120 is sized such that it doesnot extend into the Compression Element Receiving Chamber 2122 so thatit does not interfere with the insertion of the Compression Element 109.

Now referring to FIG. 22, the Pressure Cap 2140 may have a first end anda second end, wherein a Pressure Cap Rod Receiving Channel 2142 forreceiving the rod is disposed adjacent the first end of the Pressure Cap2140 and a Head Receiving Face 2144 is disposed adjacent the second endof the Pressure Cap 2140. As seen in FIG. 22, the Head Receiving Face2144 may be tapered towards the first end of the Pressure Cap 2140, andthe Pressure Cap Rod Receiving Channel 2142 and the Head Receiving Face2144 may be operatively connected. In one embodiment, the operativeconnection may be a hole in the Pressure Cap 2140 of sufficient diameterto allow passage of a drive tool through the hole as described herein.

The Pressure Cap 2140 further comprises a Guide Tab 2150. In oneembodiment the Guide Tab 2150 is disposed within the Tab Channel 2336.

As seen in FIG. 21, the Pressure Cap 2140 can be inserted into the Body2100 such that the first end and the second end of the Body 2100 areadjacent to the first end and second end of the Pressure Cap 2140,respectively. When the Pressure Cap 2140 is inserted into the Body 2100,the Tab Channel 2336 engages the Guide Tab 2150. The Tab Channel 2336 iselongated so as to allow the Pressure Cap 2140 to slideably move withinthe Body 2100 between the first end and second end of the Body 2100.Such movement is restricted by contact between the walls of the TabChannel 2336 and a Pin 2120 with the Guide Tab 2150. The lengthdimension of the Tab Channel 2336 is such that when the Head 1103A isdisposed within the Fastener Head Receiving Chamber 2105B, and theCompression Element 109 is tightened, the Guide Tab 2150 does not comein contact with the Pin 2120. Further, the length of the Tab Channel2336 is such that when the Head 1103A is inserted into the FastenerReceiving Chamber 2105B, there is enough clearance between the Guide Tab2150 and the Pin 2120 to allow for assembly.

Assembly and use of this embodiment of the Fastener Assembly 1100 issubstantially similar as to the descriptions of assembly and use alreadygiven. The differences are simply that in this embodiment theinteractions between the Guide Tab 2150, the Tab Channel 2336, and thePin 2120 discussed above take the place of the interaction between thePins 1120 and the Pin Receiving Slots 146.

While a number of embodiments of the present invention have beendescribed, it is understood that these embodiments are illustrativeonly, and not restrictive, and that many modifications may becomeapparent to those of ordinary skill in the art. For example, the presentinvention may be placed at any desired level of the spine. Further, thepresent invention may be used in conjunction with a posterior spinal rodimplantation. Further still, the controllable angulation provided by thepresent invention may be in any desired number of planes. Further still,the rod may be fixed axially and rotationally. Further still, anyelement described herein may be provided in any desired size (e.g., anyelement described herein may be provided in any desired custom size orany element described herein may be provided in any desired sizeselected from a “family” of sizes, such as small, medium, large). Togive a more specific example (which example is intended to beillustrative and not restrictive), a bone screw may be provided in adesired thread pitch, thread outer diameter, shaft outer diameter, shaftouter diameter to thread outer diameter ratio and/or length and a bodyelement may be provided in any desired inner diameter, outer diameter,lateral offset, angle and/or length. Further still, the compressionelement may have a “break-off” feature for separating from the installedportion of the compression element when a desired amount of torque hasbeen applied.

Further still, one or more of the components of the fastener assemblymay be made from any of the following materials: (a) any biocompatiblematerial (which biocompatible material may be treated to permit boneingrowth or prohibit bone ingrowth—depending upon the desire of thesurgeon); (b) a plastic; (c) a fiber; (d) a polymer; (e) a metal (a puremetal such as titanium and/or an alloy such as Ti—Al—Nb, Ti-6Al-4V,stainless steel); (f) any combination thereof.

Further still, use of the guide wire for guiding the fastener via thecannulation may be useful during a minimally invasive procedure, forexample. Further still, the bone screw may be adapted for placement incancellous bone. Further still, rather than a thread, the fastener mayemploy a hook for attachment to bone.

Further still, an outer surface of the head of the fastener, an outersurface of the rod, an outer surface of the retention ring, an innersurface of the retention ring and/or an inner surface of the body (e.g.,at any interface area between the aforementioned components) may haveone or more features for increasing friction at the interface. Forexample, any of the aforementioned components may have: a roughened ortreated surface (e.g., via sandblasting or knurling), a threadedsurface, a grooved surface, a ridged surface, a surface withprotrusions, and/or a surface with indentations. Further still, aminimum of two fastener assemblies for each rod may be used (e.g., forstabilization purposes). Further still, any type and number of featuresmay be utilized for interfacing with an installation tool (see, e.g.,the holes disposed on the outer surface of the body of the device—theseholes may mate with corresponding retractable pins of an installationtool). Further still, any steps described herein may be carried out inany desired order (and any additional desired steps may be added and/orany desired steps deleted).

What is claimed is:
 1. A fixation system, comprising: a body, whereinthe body has a first end and a second end; a body rod receiving channeldisposed adjacent the first end of the body and defined by a first walland a second wall of the body; a fastener head receiving chamberdisposed adjacent the second end of the body, wherein the fastener headreceiving chamber is tapered towards the second end of the body, andwherein the body rod receiving channel and the fastener head receivingchamber are operatively connected; a pin mounting channel positioned inthe body having a first diameter that is larger than a second diameter;a pin fixably attached to the body via the pin mounting channel, whereinthe pin includes a pin head that is larger than a pin shaft, the pinhead is configured to not extend beyond the first diameter of the pinmounting channel; a pressure cap slidably engaged with a body engagementelement, wherein the pressure cap includes pin receiving slots thatextend through an entire width of a wall of the pressure cap, andwherein the pin receiving slots are elongated so that the pressure capslidably moves within the body's first and second ends; and acompression element configured to cooperate with the body that urges arod, when the rod is disposed within the body rod receiving channel,into contact with at least part of the pressure cap.
 2. The fixationsystem of claim 1, further comprising a fastener having a head at afirst end, wherein the head of the fastener includes a drive element,wherein the pressure cap is configured to press the head of the fastenertowards the tapered end of the fastener head receiving chamber.
 3. Thefixation system of claim 1, further comprising a retention devicedisposed within the fastener head receiving chamber and configured toretain a fastener head within the fastener head receiving chamber. 4.The fixation system of claim 3, wherein the retention device is a splitring.
 5. The fixation system of claim 1, further comprising a flangedisposed over a body aperture at the second end of the body, wherein theflange has an elongated flange aperture.
 6. The fixation system of claim5, wherein the flange is integral to the body.
 7. The fixation system ofclaim 1, wherein the pressure cap comprises: a fastener head receivingface configured to contact a fastener head; and a pressure cap rodreceiving channel, wherein the pin receiving slots are configured toslideably engage with the pin.
 8. The fixation system of claim 7,wherein at least one of the pin receiving slots include a tab that isdisposed within a tab channel of the body.
 9. The fixation system ofclaim 1, further comprising a rib configured to bridge a top portion ofthe first and second walls of the body rod receiving channel and therebyprevents a rod that is positioned in the body rod receiving channel tobe moved passed the top portions of the first and second walls.
 10. Thefixation system of claim 9, wherein the body comprises an aperture inone of the walls of the body rod receiving channel.
 11. The fixationsystem of claim 1, wherein the body rod receiving channel comprises anextension of a wall of the body rod receiving channel removeablyconnected to the body at the first end.
 12. The fixation system of claim1, wherein the compression element is a set screw.